Method of securing a graft using a graft fixation device

ABSTRACT

A method of affixing a graft to bone using a the combination of a graft fixation device and an insertion member. The fixation device is useful for affixing a tissue graft to a bone or other body surface. The graft fixation device comprises two implantation members connected by a connecting member. The implantation members have longitudinal passageways therethrough. The insertion device member similarly has a longitudinal passage.

This is a Continuation-In-Part application of commonly assignedcopending U.S. patent application Ser. No. 09/360,367 filed on Jul. 23,1999, which is incorporated by reference.

TECHNICAL FIELD

The field of art to which this invention relates is surgical fasteningdevices, in particular, surgical fastening devices for fixating tissuegrafts to bone.

BACKGROUND OF THE INVENTION

The medical technology associated with tissue engineering has advancedat a rapid pace. In particular, it is now known to harvest cells fromthe human body, for example, chondrocytes and fibrochrondrocytes fromthe knee joint. These autologous cells are then cultured in a laboratoryenvironment on a bioabsorbable matrix. The matrix will typically have ashape substantially similar to the tissue section which needs to bereplaced. After a sufficient period of time in an appropriate culturemedium at the proper environmental conditions, the harvested cells willgrow on the matrix to form an implantable section of tissue havingsubstantially the same physical configuration as the section of tissuewhich needs to be replaced in the patient. Such a tissue-engineeredconstruct, consisting of cells on the matrix (or, alternatively,consisting of a matrix alone without cells), is then affixed to the bonesite using conventionally known surgical fasteners including sutures,periosteal coverings, or fibrin glue.

The advantages of tissue engineering are many, not the least of whichis, for example, that it is now possible to replace cartilage withliving cartilage tissue. In addition, the likelihood of rejection of thetissue implant is minimized since the cartilage tissue which has beengrown in-vitro is identical to the autologous cartilage of the patient.

Although existing matrix fixation devices are adequate for theirintended use, there are also some disadvantages attendant with theiruse. First of all these fixation devices are generic in the sense thatthey are not specifically designed for matrix fixation to bone or softtissue, but can be used for a variety of surgical procedures. Otherdisadvantages include the difficulty in using many of these devices in aminimally invasive arthroscopic procedure. Additional disadvantagesinclude the difficulty and surgical challenge of harvesting a piece ofperiosteum for use as a periosteal flap, the significant patientmorbidity associated with such harvesting, and the difficulty insuturing such a thin, compliant material to surrounding tissue.

Accordingly, there is a need in this art for novel fixation devices thatwill effectively affix a matrix of tissue-engineered tissue to a bone orother anchoring site so that the tissue may continue to grow andregenerate in the patient's body.

DISCLOSURE OF THE INVENTION

Therefore, it is an object of the present invention to provide afixation device that effectively fixates a tissue-engineered matrix to abone or other anchoring site, thereby enabling the implanted matrix toremain in place while the tissue continues to grow and regenerate.

It is a further object of the present invention to provide such a devicefor fixating a matrix to a bone site which is easily installed using anarthroscopic procedure or an open procedure.

It is yet a further object of the present invention to provide such adevice for fixating a matrix to a bone site which does not requiresutures or suture knot tying.

It is still yet a further object of the present invention to provide asurgical method for fixating a matrix utilizing such a device in alocation within a patient's body.

Accordingly, a graft fixation device is disclosed. The graft fixationdevice has first and second implantation members. The members areelongated and preferably have a cylindrical configuration. The membersalso have distal ends, proximal ends, and longitudinal axes. There arelongitudinal passages extending through the entire length of eachimplantation member. The members have outer surfaces. The implantationmembers are connected to each other by a rod member having first andsecond ends and a central section. The first end of the rod memberextends from the proximal end of the first implantation member and thesecond end of the rod member extends from the proximal end of the secondimplantation member. The rod member is preferably relatively rigid andmay be configured to have a variety of geometric shapes, for example, aninverted “U” shape. However, the rod member may also be flexible. Therod member maintains the implantation members at a relatively fixeddistance from each other. The central section of the rod member isdesigned to engage a section of a tissue-engineered matrix implant. In apreferred embodiment, the implantation members have a series of ridgesextending out from the outer surfaces of the implantation members toassist in preventing withdrawal from a bone site or other anchoring siteafter the implantation members are implanted into previously-createdbore holes.

Yet another aspect of the present invention is a method of using thegraft fixation device of the present invention to affix a matrixcontaining tissue-engineered tissue to a bone.

Still yet another aspect of the present invention is a graft fixationdevice combination which is the combination of a fixation device and aninsertion member. The fixation device has a first implantation member.The implantation member has a longitudinal axis, a proximal end, adistal end, an outer surface, and a longitudinal passage therethrough.The fixation device also has a second implantation member. The secondimplantation member has a longitudinal axis, a proximal end, a distalend, an outer surface, and a longitudinal passage therethrough. Eachimplantation member has a proximal annular face on its proximal endsurrounding the longitudinal passages. There is a connecting memberconnecting the first and second implantation members. The connectingmember has a central section, a first end extending from the firstimplantation member and a second end extending from the secondimplantation member.

There are a pair of insertion devices. Each insertion device is a memberhaving a proximal end, a distal tapered end and a longitudinal passagetherethrough. The distal end of each implantation member is inengagement with the proximal end of an insertion device.

Another aspect of the present invention is the above describedcombination wherein an insertion device is mounted to the distal end ofeach implantation member.

Yet another aspect of the present invention is a method of mounting amatrix to tissue, in particular, bone using the previously-describedcombination. The combination of a graft fixation device and a pair ofinsertion devices is provided. The fixation device has a firstimplantation member, said implantation member having a longitudinalaxis, a proximal end, a distal end, an outer surface, and a longitudinalpassage therethrough. The fixation device also has a second implantationmember, said second implantation member having a longitudinal axis, aproximal end, a distal end, an outer surface, and a longitudinal passagetherethrough. There is an optimal proximal annular face on the proximalends of the first and second implantation members surrounding theproximal opening to longitudinal passage. A connecting member connectsthe first and second implantation members, the connecting member has acentral section, a first end extending from the first implantationmember and a second end extending from the second implantation member.As mentioned above, a pair of insertion devices are also provided. Eachinsertion device consists of a member having a proximal end, a distaltapered end and a longitudinal passage therethrough. The distal end ofeach implantation member is in engagement with the proximal end of aninsertion device. Optionally, an insertion member is molded into thedistal end of each implantation member. Next, the combination of thefixation device and insertion members is mounted to an insertioninstrument having a pair of spaced apart prongs, said prongs havingdistal ends and distal pointed tips extending therefrom, such that theprongs are contained within the passages of the implantation members andinsertion members, and such that the distal tips of the prongs extendbeyond the distal ends of the insertion members, and the distal end ofeach implantation member engages the proximal end of each insertionmember. A matrix is placed upon a bone. And, then the implantationmembers and insertion members are driven through the matrix into thebone, thereby securing the matrix to the bone.

Yet another aspect of the present invention is the above-describedmethod, wherein the insertion members are mounted to the implantationmembers prior to mounting onto the prongs of the insertion instrument,such that the combination is mounted on the prongs in a single step.

These and other features and advantages of the present invention willbecome more apparent from the following description and accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a graft fixation device of the presentinvention.

FIG. 2 is a cross-sectional view of the graft fixation device of FIG. 1taken along view line 2—2.

FIGS. 3-6 illustrate a surgical procedure for affixing a matrix to boneusing the graft fixation device of the present invention.

FIG. 7 is an illustration of a graft fixation device of the presentinvention after the implantation members have been implanted in boreholes in bone illustrating the device affixing a matrix securely to thesurface of a bone.

FIG. 8 is a cross-sectional view of the graft fixation device of FIG. 7implanted in bone, and taken along View Line 8—8.

FIG. 9 is an alternative embodiment of a graft fixation device of thepresent invention having two connecting members.

FIG. 10 is a perspective view of an instrument useful for making boreholes in bone into which the implantable members of the graft fixationdevices of the present invention may be emplaced.

FIG. 11 is a perspective view of an instrument useful for implanting thedevice of the present invention into bore holes made in bone.

FIG. 12 is a view of a tissue engineered matrix secured to a bone withseveral graft fixation devices of the present invention.

FIG. 13 is a perspective view of an alternate embodiment of a graftfixation device of the present invention.

FIG. 14 is a side view of the graft fixation device of FIG. 13.

FIG. 15 is an end view of the graft fixation device of FIG. 14.

FIG. 16 is a cross-sectional view of the graft fixation device of FIG.14, taken along View-Line 16—16.

FIG. 17 is a cross-sectional view of the tissue retention member of thegraft fixation device of FIG. 14, taken along View-Line 17—17.

FIG. 18 is a perspective view of an insertion member useful to insert agraft fixation member of the present invention.

FIG. 19 is an exploded perspective view of an insertion instrument, agraft fixation device, and two insertion members.

FIG. 20 is a side view of the distal end of the insertion instrument, agraft fixation device, and insertion members engaged in bone, prior toremoval of the insertion device.

FIG. 21 is a cross-sectional view taken along View-Line 21—21 of FIG. 20of the prong of the insertion instrument, and a section of the retentionmember engaged in a longitudinal groove of the prong.

FIG. 22 is an exploded perspective view of the distal end of aninsertion instrument of the present invention, illustrating a removabledistal end assembly for creating bore holes in bone for receiving thefixation devices of the present invention, wherein the assembly has anend member and pins.

FIG. 23 is a cross-section of the assembly end member of FIG. 22, takenalong View-Line 23.

FIG. 24 is a perspective view of the assembly end of FIG. 22, completelyassembled and ready for use.

FIG. 25 is a cross-sectional view of the end assembly of FIG. 24, takenalong View-Line 25—25.

FIG. 26 is an exploded perspective view an insertion instrument of thepresent invention having a removable distal end assembly useful forinserting the graft retention members of the present invention into boreholes in a bone, having an end assembly member and two pins; when usedwith inserting members, the instrument can be used to emplace thefixation device directly into bone without first forming bone boreholes.

FIG. 27 is a cross-sectional view of the end assembly member of FIG. 26.

FIG. 28 is a perspective view of the distal end of the insertioninstrument of FIG. 26, having the end assembly member and prongs fullyassembled and mounted.

FIG. 29 is a cross-sectional view of the distal end of the insertioninstrument of FIG. 28 take along View-Line 29—29.

FIG. 30 is a cross-sectional view of the instrument of FIG. 29 takenalong View-Line 30—30.

FIG. 31 illustrates a fixation device of the present member having aninsertion member molded into the distal end of each implantation member.

FIG. 32 is a cross-sectional view of the fixation device of FIG. 31.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The graft fixation devices of the present invention can be made fromconventional bio-compatible materials, including absorbable andnon-absorbable materials, as well as biodegradable materials. Thenon-absorbable materials which can be utilized include conventionalbiocompatible materials such as stainless steel, polyethylene, Teflon,Nitinol, non-absorbable polymers, other bio-compatible metals, ceramics,combinations thereof and the like. The absorbable materials which can beused to manufacture the graft fixation devices of the present inventionwill typically include those conventional bioabsorbable or bioresorbablematerials known in this art which can be effectively molded or machined.The bio-absorbable and bio-resorbable materials include polylactic acid,polydioxanone, polycaprolactone, polyglycolic acid, polygalactic acid,other known biocompatible bioabsorbable and bioresorbable polymers,ceramics, composites, combinations thereof and the like and equivalentsthereof.

Referring now to FIGS. 1-2, a preferred embodiment of a graft fixationdevice 10 of the present invention is illustrated. The graft fixationdevice 10 is seen to have implantation members 20. The implantationmembers 20 are seen to be elongated members, preferably having asubstantially cylindrical shape. The members 20 may have other geometricshapes including conical, pyramidal, polygonal, cubic, spherical, etc.The implantation members 20 are seen to have distal ends 22 and proximalends 24. Each implantation member 20 is seen to have an outer surface 28and a longitudinal axis 29. Each member 20 is also seen to havelongitudinal passage 35 extending therethrough. The implantation members20 are also seen to have optional frustoconical ends 30, and proximalendface surfaces 32. Although it is preferred that endface surfaces 32be flat, endface surface 32 may also be angled, concave, convex, etc.Endface surface 32 is seen to have central circular opening 36 incommunication with passage 35. Preferably, central opening 36 will havea circular cross-section, but it may have other geometric cross-sectionsas well including elliptical, polygonal, square, rectangular,combinations thereof and the like. Members 20 are also seen to havedistal end face surfaces 37 having circular openings 38 in communicationwith passages 35. As shown with the optional frustoconical end 30, theannular end face surface 37 is of de minimis thickness around opening38, however this thickness would increase in the absence of afrustoconical end. Also seen to extend out from the surface 28 of member20 are a series of optional projections 40 having tissue engagementedges 44. Without the projections 40, the surface 28 of the member 20will be smooth.

The device 10 is seen to have graft retention member 50 connecting theimplantation members 20. Retention member 50 is seen to be a rod-likemember having first end 52, second end 54 and central section 55. Firstend 52 is seen to extend from proximal endface surface 32 of the firstmember 20 while end 54 is seen to extend up from the proximal endfacesurface 32 of the other member 20. The ends 54 and 52 of retentionmember 50 may also if desired extend from or be mounted to any sectionof outer surface 28. The connecting member 50 is seen to be preferablybent or shaped into three segments including top segment 55 and legsegments 56. The top segment 55 is seen to be substantiallyperpendicular to the leg segments 56. Although it is preferred thatconnecting member 50 have an inverted “U” configuration, the connectingmember 50 may have other geometric configurations includingsemicircular, arced, curved, triangular, polygonal, U-shaped, and thelike and combinations thereof. The ends 52 and 54 of connecting member50 may be permanently affixed to the implantation members 20, or may beremovably attached thereto in a conventional manner. Member 50 may berigid or flexible. Member 50 will have a sufficient surface area toeffectively retain a tissue-engineered matrix in place on a bone orother body surface. Preferably, connecting member 50 will have acircular cross-section, but may have other geometric cross-sections aswell including elliptical, polygonal, square, rectangular, combinationsthereof and the like. Member 50 may be rigid or flexible, and may have asingle filamentary structure or have multiple interconnected filamentsor members.

Referring now to FIGS. 3-8, the use of the graft fixation devices 10 ofthe present invention in a surgical procedure is illustrated. Referringfirst to FIG. 3, the initial step, prior to the installation of a matrixcontaining a tissue-engineered tissue using a graft fixation device 10of the present invention, is to drill or “tap” two bore holes 200 into abone 210, for example, subchondral bone in the knee joint. The boreholes 200 are seen to be cylindrical holes having a bottom 208 and anopen top 202 and side walls 205. Optionally, the bore holes may be bonetunnels with a continuous passage and no bottom, or an open bottom. Itis particularly preferred to tap the holes in the bone by using aninstrument 400 as illustrated in FIG. 10 which has a proximal sectionconventionally referred to in this art as a “slap hammer” section. Theterm “tapping” or “tap” as used herein is defined to mean a procedurewherein the distal pointed prongs 420 extending from the distal end 415of the shaft 405 of instrument 400 are located over a bone site, and theproximal end 410 of instrument 400 is tapped or hit with slidable hammerhandle 450 (of the “slap hammer”), which slides on shaft 460 betweenproximal end 410 and proximal stop 470, to form the bone bore holes 200.The distal end 465 of shaft 460 is connected to proximal end 411.Proximal stop 470 is mounted to proximal end 467. Hammer handle 450 isseen to have grasping section 451, collars 455 and longitudinal passage457. Those skilled in the art will appreciate that a similar pointedinstrument may be used to “tap” in the bore holes into bone, that is,any instrument having a nail-like distal end. In addition, although notpreferred, one bone bore hole at a time may be “tapped” in. If thesurgeon decides to drill the bore holes into bone, any conventionalsurgical drilling apparatus may be used. After the bore holes 200 areformed into the bone 210, the matrix 220 containing tissue-engineeringtissue is placed upon the bone surface 201 by the surgeon as seen inFIG. 4. Next, the graft fixation device 10 is mounted on to theinsertion instrument 250. Insertion instrument 250, as illustrated inFIG. 11, is seen to be an elongated rod 260 having a proximal end 262and a distal end 264. Mounted to the distal end 264 of the rod 260 isthe depth stop 290. The depth stop 290 is seen to be a substantiallyrectangular member which is mounted perpendicular to the longitudinalaxis 251 of the rod 260. Depth stop 290 is seen to have bottom 292.Extending distally from the bottom 292 of plate member 290 is a pair ofparallel, spaced-apart, mounting prongs 270. The mounting prongs 270 areseen to be substantially rod-like members having distal pointed tips 277and proximal ends 272. The prongs 270 are seen to have first section 273and distal section 275. Section 273 is seen to have a greatercross-sectional dimension than distal section 275 such that the entiresection 275 is insertable into passages 35 of members 20, while proximalsection 273 is not insertable therein. Instrument 250 is also seen tohave a “slap hammer section” consisting of proximal shaft 300 extendingfrom proximal end 262, slidable hammer handle 320 (the “slap hammer”)which is slidable upon shaft 300 between proximal end 262, and proximalstop 330. Hammer handle member 320 is seen to have grasping section 325,end collars 327 and longitudinal passage 329. The graft fixation device10 is mounted to the insertion instrument 250 by sliding theimplantation members 20 onto the prongs 270 such that the distalsections 275 of members 270 are engaged within the longitudinal passages35 of members 20 and distal points 277 protrude beyond the end of distalendface surfaces 37. Then, as seen in FIGS. 5 and 6, the instrument 250is manipulated such that the graft fixation device 10 is insertedthrough matrix 220 and into bone 210 by moving the implantation members20 mounted on prongs 270 into the bore holes 200 such that the members20 are engaged in the bore holes 200, and such that the tissueengagement section 55 of the retention member 50 engages the matrix 220such that the matrix 220 is firmly engaged against the surface 201 ofthe bone 210. If desired, holes may be cut into matrix 220 prior toinsertion of device 10. Then, as seen in FIG. 7, the insertioninstrument 250 is withdrawn proximally causing the prongs 270 to bewithdrawn from the passages 35 of the implantation members 20, therebyleaving the graft fixation device 10 engaged in the bone bore holes, andcausing the matrix 220 to be maintained in engagement with the surface201 of bone 210. The “slap hammer” section of instrument 250 may assistin removal of the prongs. A cross-sectional view illustrating the device10 engaged in bone 210 while maintaining the matrix 220 on bone surface201 is seen in FIG. 8.

FIG. 12 illustrates a matrix 220 mounted to bone surface 201 of bone 210having multiple fixation devices of the present invention installed tosecure the matrix 220. The number, anatomical location and orientationof fixation devices 10 necessary to provide sufficiently effectivefixation will vary with the size and type of implant or matrix, the typeof tissue, the age of the patient, the size of the patient's defect, thesize of the fixation devices, the material of construction of thefixation devices, the load on the tissue at the repair site, etc.

Those skilled in the art will appreciate that the size of the fixationdevices of the present invention will vary in accordance with a numberof variables including the specific design of the device, the materialsof construction, the specific application for the devices, the type ofsurgical procedure, etc. Similarly, the size of the matrices fixatedwith these devices will similarly vary. The Figures which are part ofthis specification are merely schematic and illustrative of the deviceand method of the present invention; the actual dimensions of thedevices and matrices may vary in practice.

The following example is illustrative of the principles and practice ofthe present invention although not limited thereto.

EXAMPLE

Six sheep were prepared for a surgical procedure using standard asepticsurgical techniques including the use of fully sterilized instrumentsand equipment, and conventional anesthesia procedures and protocols. Thesurgeon then created 7 mm diameter chondral (full thickness cartilage)defects on a weight-bearing area of the medial femoral condyle and inthe trochlear groove in the right stifle (knee) in each of the sixskeletally mature sheep. Defects were created using a specialized drillwith a depth-stop to prevent subchondral bone exposure or penetration.The base surfaces of all the defects were then microfractured with aspecialized micropick tool to provide access for cellular migration. Thesubjects were then separated into three groups of two subjects each:

Group 1: defect filled with a collagen matrix, fixed with the graftfixation device of the present invention.

Group 2: defect filled with a collagen matrix, fixed with 9-0 absorbableVicryl™ suture (interrupted stitch technique, approximately 12 strandsper matrix).

Group 3: unfilled defect (control group).

Both defects in a given stifle received the same treatment or served ascontrols.

For the two sheep in Group 1, after a defect had been created andmicrofractured, a punch tool 400 was used to create the two requisitebore holes in the subchondral bone to receive one graft fixation deviceof the present invention. Only one polydioxanone device (4 mm tip-to-tipdistance) was used to attach each matrix. To create the bore holes, thepunch tool was centered in the defect, oriented in the sagittal plane,and hit or “tapped” with a slap hammer repeatedly until it penetratedseveral millimeters into the subchondral bone. Next, a 7 mm diametercircular collagen matrix, saturated with saline, was placed in thedefect and then blotted dry to remove excess saline. When the insertertool 250 was loaded with the graft fixation device 10 of the presentinvention, the device and inserter tool were centered above the matrixand oriented in the sagittal plane. The surgeon then located thepreviously created bore holes by slowly advancing the distal tips of theinserter through the matrix. Once the surgeon located the holes with theinserter tips, a hammer was used to fully advance the inserter tool (andimplantation members 20 of the fixation device 10) through the matrixand into the subchondral bone. The inserter tool had a depth stop toprevent the implantation members 20 from being inserted too deeply,thereby assuring the proper placement of the implantation membersthrough the matrix. The insertion was completed when the connectingretention member between the two implantation members initially startedto compress the collagen matrix, thereby indicating secure fixation withthe underlying subchondral bone. After the two defects in a given stiflehad each been repaired with a matrix and fixation device, the stifle wasclosed and the sheep was allowed to recover. It was noted by the surgeonthat it took approximately one minute to attach a matrix with a fixationdevice of the present invention (Group 1), versus approximately 15minutes to attach a matrix with suture alone and the requisite suturemanipulation and knot tying (Group 2).

Two weeks after the surgeries were completed, the knee joints weresurgically opened for examination. Gross macroscopic assessment of thejoints demonstrated that all four matrices held by the graft fixationdevice of the present invention were fully intact. However, all fourmatrices held by sutures alone were only partially intact with, onaverage, approximately 30% of the sutures broken on any given matrix.

Another embodiment of the fixation device of the present inventionhaving multiple retention members is seen in FIG. 9. The device 300 isseen to have a pair of implantation members 310. The implantationmembers 310 are substantially cylindrical members having longitudinalaxis 311, distal ends 314 and proximal ends 312. Each implantationmember 310 is seen to have a longitudinal passage 320. The members 310are seen to have a distal frustoconical end 330, outer surface 350, andridges 355 extending outward from surface 350. The members 310 are seento be connected by a pair of retention members 340, having first andsecond ends 342 and 344 respectively.

Yet another embodiment of a fixation device of the present invention isillustrated in FIGS. 13-17. The graft fixation device 500 is seen tohave implantation members 520. The implantation members 520 are seen tobe elongated members, preferably having a substantially cylindricalshape. The members 520 may have other geometric shapes includingconical, pyramidal, polygonal, cubic, spherical, etc. The implantationmembers 520 are seen to have distal ends 522 and proximal ends 524. Eachimplantation member 520 is seen to have an outer surface 528 and alongitudinal axis 529. Each member 520 is also seen to have longitudinalpassage 535 extending therethrough. The implantation members 520 arealso seen to have optional frustoconical ends 530, and proximal end facesurfaces 532. Although it is preferred that endface surfaces 532 beflat, endface surfaces 532 may also be angled, concave, convex, etc.Each endface surface 532 is seen to have central circular opening 536 incommunication with passage 535. Preferably, central opening 536 willhave a circular cross-section, but it may have other geometriccross-sections as well including elliptical, polygonal, square,rectangular, combinations thereof and the like. Members 520 are alsoseen to have distal end face surfaces 537 having circular openings 538in communication with passages 535. Preferably, end face surfaces 537have a sharp edge configuration, but may also have various widths with arounded or flat configuration. As shown with the optional frustoconicalend 530, the annular end face surface 537 is of de minimis thicknessaround opening 538, however this thickness would typically increase inthe absence of a frustoconical end. However, although not preferred,even with a frustoconical, the end surface 537 could have various widthsas previously mentioned. Also seen to extend out from the surface 528 ofmember 520 are a series of optional projections 540 having tissueengagement edges 544. Without the projections 540, the surface 528 ofthe member 520 will be smooth, however, it will be appreciated thatsurface 528 could be rough, or could have a variety of conventionalprojections such as cones, hemispheres, rods, hooks, etc., and the likeand equivalents thereof.

The device 500 is seen to have graft retention member 550 connecting theimplantation members 520. Retention member 550 is seen to be a band-likemember preferably having an oval cross-section. The retention member 550is seen to have first end 552, second end 554 and central section 555.First end 552 is seen to extend up from proximal endface surface 532 ofthe first member 520 while end 554 is seen to extend up from theproximal endface surface 532 of the other member 520. A section 557 ofend 552 is seen to extend out from section 539 of surface 528, whilesection 558 of second end 554 is also seen to extend out from a section539 of surface 528. The ends 554 and 552 of retention member 550 may ifdesired extend from or be mounted to any section of outer surface 528.The connecting member 550 is seen to be preferably bent or shaped intothree segments including top segment 555 and leg segments 556. The topsegment 555 is seen to an arc shaped member, and the leg segments 56 areseen to be preferably perpendicular to surfaces 532. Although it ispreferred that connecting member 550 have an inverted “U” configuration,the connecting member 50 may have other geometric configurationsincluding semicircular, arced, curved, triangular, polygonal, V-shaped,and the like and combinations thereof. The ends 552 and 554 ofconnecting member 550 may be permanently affixed to the implantationmembers 520, or may be removably attached thereto in a variety ofconventional manners, for example, a ball and socket joint, a plugjoint, etc. Member 550 may be rigid or flexible. Member 550 will have asufficient surface area to effectively retain a tissue-engineered matrixin place on a bone or other body surface. Preferably, connecting member550 will have an oval cross-section, but may have other geometriccross-sections as well including circular, elliptical, polygonal,square, rectangular, combinations thereof and the like. Member 550 maybe rigid or flexible, and may have a single filamentary structure orhave multiple interconnected filaments or members.

Another aspect of the present invention is a distal insertion member(device) useful with the fixation devices of the present invention. Asseen in FIG. 18, the insertion device 600 is seen to be a substantiallycylindrical member having proximal end 610 and distal end 620, althoughdevice 600 may have other configurations as well. Proximal end 610 isseen to have a flat end surface 612. Frustoconical end section 630 isseen to extend distally from distal end 620. If desired, distal end 620can have any tapered or curved configuration, but it is preferred thatit have a frustoconical end section extending therefrom. Thefrustoconical end section 630 is seen to have outer surface 632 anddistal tip 640. The member 600 is also seen to have exterior surface650. Extending through member 600 is the longitudinal passage 660 havingfirst circular opening 665 in communication therewith, and secondcircular opening 667 in tip 640 in communication therewith. Theinsertion members 600 are used in combination with the fixation membersof the present invention to engage the fixation member in bonesimultaneously with tapping the bore holes into bone, therebyeliminating the need for a separate step to form the bore holes prior toinserting the fixation member.

Referring to FIGS. 19-21, the previously mentioned combination of aninsertion member 600 and a fixation member 500 is illustrated.Initially, a fixation member 500 is mounted to prongs 700 extending fromthe distal end 415 of the shaft 405 of instrument 400. Each prong 700 isseen to have first cylindrical section 710 extending from the distal end415 of the shaft 405. Each cylindrical section 710 is seen to haveproximal end 711 and distal end 712, and receiving grooves 715.Extending from the distal end 712 of each first section 710 is thecentral pin section 720. Central pin section 720 is seen to haveproximal end 722 and distal end 724. Extending distally from distal end724 of central pin section 720 is the distal pin member 730. Distal pinmember 730 is seen to have proximal end 732 and distal pointed end 734.

If desired, the insertion member 600 may be molded into or affixed tothe distal end of an implantation member 520, thereby forming a unitarystructure as seen in FIG. 31 and FIG. 32. In addition, the insertionmember 600 may be mounted to the distal end of an implantation member520 in a conventional manner by gluing, cementing, mechanical fastening,friction fit, and the like and equivalents thereof.

The combination of the insertion members 600 and fixation members, suchas fixation member 500 of the present invention, are used to affix amatrix to bone in the following manner. Initially, the implantationmembers 520 of a fixation device 500 are placed upon prongs 700 of aninstrument 400 such that the leg members 556 are at least partiallyengaged in grooves 715 in first section 710 (see FIG. 21), and,intermediate sections 720 of pin members 700 are engaged in passages 535of implantation members 520, while pin members 730 extend out from thedistal ends of the implantation members 520. Then, insertion members 600are placed over the pin members 730, such that the pin members 730 areengaged in passages 660, and such that the pointed piercing ends 734extend beyond the distal ends 640 of the insertion member 660. Then, thetool 400 and the assembly consisting of fixation device 500 andinsertion member 600 is placed over a tissue matrix 220 placed upon abone 210. The piercing points are then pressed through matrix 220 tocontact the surface 211 of bone 210. A slap-hammer section of instrument400 is engaged to drive the piercing points 734, insertion members 600and implantation members 520 into the bone 210 as bore holes 200 areformed in the bone. The instrument 400 is then withdrawn proximately,thereby removing the intermediate sections 720 of prongs 700 from theimplantation members 520 and the pin members 730 from the insertionmembers 600, leaving the insertion members 600 and the implantationmembers 520 securely in the bone (as seen in FIG. 20). This completesthe affixation of the matrix 220 to the bone 210 using a single step,wherein the bore holes in the bone are formed simultaneously asinsertion members 600 and fixation device 500 are emplaced in the bone.

It is particularly preferred to use conventional remote visualizationsurgical procedures when inserting the fixation devices of the presentinvention. For example, inserting a scope through a trocar cannula intothe joint or body cavity, while insufflating the body cavity or joint.

The insertion members 600 will typically be made from a strong, hard,bioabsorbable material such that they can be driven into bone withoutfracturing or breaking. Examples of the types of materials which can beused to make the insertion member 600 include polylactic acid,polyglycolic acid, tricalcium phosphate, calcium phosphate, tetracalciumphosphate and hydroxyapatite, and any copolymers, mixtures or blendsthereof. Although not preferred, it is possible to make the insertionmembers from a conventional biocompatible material which is notbioabsorbable or biodegradable, such as titanium, stainless steel,ceramics, Nitinol and the like and equivalents thereof. The insertionmember 600 assists in forming the bore holes 200 while protecting theimplantation members 520.

FIGS. 22-23 illustrate a disposable distal end assembly 800 for aninstrument 400 of the present invention. When using the disposableassembly 800, it is preferable that the distal end 415 of the shaft 405of instrument 400 have screw threads 418, although other conventionaldetachable mounts may be used, for example a bayonet-type mount, lockinglevers and tabs, male and female mating sections, etc. As seen in FIGS.22-25, the assembly 800 consists of housing 810 having proximal end 811and distal end 817. Housing 810 is seen to have hollow cavity 815therein. Cavity 815 is seen to be in communication with proximal endopening 812 and distal end openings 820. Member 810 is seen to haveouter surface 822. Outer surface 822 is preferably knurled to facilitatethe grasping and turning of the housing 810. Housing 810 is further seento have distal end surface 825. The outer surface 822 is seen to have atapered section 823 which tapers toward end face 825. Contained withincavity 815, on inner surface 818 are the screw threads 819. Assembly 800is also seen to have driving pin members 830. Each driving pin member830 is seen to have proximal disk member 832 mounted to proximal end831, shaft section 834 and distal pointed end 838. Surrounding eachopening 820 on the interior of the member 810 are the annular recesses840. The assembly 800 is mounted to the distal end 415 of the instrument400 in the following manner. The pins 830 are inserted into cavity 815and through openings 820 such that the shafts 834 and distal piercingpoints 838 extend through end face 825, and the disk members 832 arecontained within the annular recesses 840. Then, the housing 810 ismounted upon the threads of distal end 415 such that threads 418 engagemating threads 819, and screwed further such that the proximal endsurfaces 833 of the disk members 832 are in contact with the distal endface 416 of distal end 415. After use in a surgical procedure, theassembly 800 is removed and discarded. A new sterile assembly 800 isutilized with a cleaned and sterilized instrument 400 for each newprocedure.

Referring now to FIGS. 26-30, a disposable end assembly 900 for mountingto an insertion instrument 250 is illustrated. The insertion member 250is seen to have distal end 264, having endface 265 and screw threads266. The assembly 900 is seen to have housing 950. Housing 950 hasproximal end 952 and distal end 956 and exterior surface 954. Extendingfrom distal end 956 is the plate member 960. Plate member 960 is seen tohave distal surface 962. The exterior surface 954 is seen to haveoptional knurling and distal tapered section 957 tapering into platemember 960. Housing 950 is seen to have internal cavity 955. Housing 950is also seen to have proximal opening 951 in communication with cavity955 and distal openings 970 also in communication therewith. Housing 950is seen to have internal screw threads 959 extending from internalsurface 958. Also contained within the interior of housing 950 in thedistal end 956 is the recessed groove 980. Assembly 900 is mounted tothe distal end 264 of instrument 250 in the following manner. Pins 910are inserted through cavity 950 and openings 970 such that proximalmembers 922 are engaged in groove 980. Sections 920 and 930 of pins 910extend through openings 970. Sections 920 are seen to have grooves 925.Then, the housing 950 is screwed on to distal end 264 such that thethreads 266 engage the mating internal threads 959 of housing 950. Thehousing is tightened until the distal end surface 265 of the distal end264 engages the top surfaces 923 of members 922. After a surgicalprocedure, the assembly 900 is removed from instrument 250 anddiscarded. A new sterile assembly 900 is utilized with a cleaned andsterilized instrument 250 for each new procedure.

The fixation devices of the present invention, and the combination ofthe fixation devices with insertion members, and methods of using suchdevices and combinations, have many advantages. The advantages includeproviding a fast and routine way to fixate a matrix of tissue engineeredtissue or other tissue. The fixation devices and combination, becausethey eliminate the need for suture knot tying, can be utilized inarthroscopic surgical procedures that require a minimum of surgicalincisions and thus greatly reduce patient morbidity. In addition, thefixation devices and combination have been demonstrated to provideexcellent matrix fixation without damaging the surrounding normalcartilaginous tissue, unlike the conventional fixation of chondraldefect matrices with traditional suture that must be passed through (andthus damage) the surrounding tissue.

Although this invention has been shown and described with respect todetailed embodiments thereof, it will be understood by those skilled inthe art that various changes in form and detail may be made withoutdeparting from the spirit and scope of the claimed invention.

We claim:
 1. A method of mounting a matrix to tissue, comprising thesteps of: providing a graft fixation device comprising the combinationof: I. A fixation device, comprising: a first implantation member, saidimplantation member having a longitudinal axis, a proximal end, a distalend, an outer surface, and a longitudinal passage therethrough; a secondimplantation member, said implantation member having a longitudinalaxis, a proximal end, a distal end, an outer surface, and a longitudinalpassage therethrough; a connecting member connecting the first andsecond implantation members, the connecting member having a centralsection, a first end extending from the first implantation member and asecond end extending from the second implantation member; and, II. Apair of insertion devices, each insertion device comprising: a memberhaving a proximal end, a distal tapered end and a longitudinal passagetherethrough, wherein the distal end of each implantation member is inengagement with the proximal end of an insertion device; mounting thecombination to an insertion instrument having a pair of spaced apartprongs, said prongs having distal ends and distal tips extendingtherefrom, such that the prongs are contained within the passages of theimplantation members and the passages of the insertion members, suchthat the distal tips of the prongs extend beyond the distal ends of theinsertion members; placing a matrix onto the surface of a bone; andinserting the combination of the insertion members and the implantationmembers through the matrix and into the bone thereby forming bore holeswhile simultaneously emplacing the implantation members in the bone,thereby securing the matrix to the bone.
 2. The method of claim 1,wherein the implantation members have a series of ridges extending fromthe outer surfaces thereof.
 3. The method of claim 1, wherein theconnecting member is shaped into a configuration having a centralsection and leg members, wherein the leg members are substantiallyparallel to the longitudinal axes of the implantation members, and thecentral section is substantially perpendicular to the rod members. 4.The method of claim 1, wherein the connecting member has a semi-circularconfiguration.
 5. The method of claim 1 wherein the implantation membersadditionally comprise a frustoconical end extending from the distal endof the first implantation member and the distal end of the secondimplantation member.
 6. The method of claim 1 wherein the implantationmembers have a cylindrical configuration.
 7. The method of claim 1,wherein the distal tip of each comprises a piercing point extending fromthe distal end.
 8. The method of claim 1, wherein each prong comprises adistal section having a cross-section and a proximal section having across-section, wherein the cross-section of the proximal section isgreater than the cross-section of the distal cross-section.
 9. Themethod of claim 1, wherein each prong has a circular cross-section. 10.The method of claim 1 wherein the insertion member comprises abioabsorbable material selected from the group consisting of polylacticacid, polyglycolic acid, tricalcium phosphate, calcium phosphate,tetracalcium phosphate and hydroxyapatite, and copolymers, mixtures andblends thereof.
 11. The method of claim 1 wherein the insertion membercomprises a biocompatible material selected from the group consisting oftitanium, stainless steel, ceramic, and Nitinol.
 12. The method of claim1 wherein an insertion member is affixed to each implantation memberprior to mounting on the prongs of the insertion instrument.
 13. Themethod of claim 12 wherein the insertion members are co-molded with thefixation device.
 14. The method of claim 12 wherein the insertion memberis affixed by gluing.
 15. The method of claim 1 conducted by using aremote visualization scope.